1. Technical Field
The present invention relates to an image processor, a computer readable medium and a computer data signal.
2. Related Art
Conventionally, when reading an image on one side of an original sheet which has images on both sides thereof or an image of an original sheet on which other original sheets are stacked, there has been occurring a so-called back-side image reading in which not only the target image but also the image on the back side of the original sheet or the image on the one other original sheet stacked on the original sheet are read. As one of techniques which eliminate a non-target image which is read from a back side of an original sheet, a technique is known in which images on both sides of an original sheet are read together, so that the image read from the back side of the original sheet is eliminated by referring to the images on both the sides of the original sheet.
In a method for removing a non-target image which is read together with a target image of an original sheet by referring to the image only on one side thereof, the removal of the non-target image has been realized by performing a so-called background removing process. The background removing process is such that a gradation correction is performed on the read image according to some certain fixed value or detected background level.